I've still yet to get it to work completely. 
Let's start with what I've successfully done -
In class_template.php's assignTemplateVars() function I've added:
	Code:
	$mysidia = Registry::get("mysidia");
$this->assign("logged_in",$mysidia->user->isloggedin);
$this->assign("username",$mysidia->user->username);
$this->assign("cash",$mysidia->user->getcash());
$this->assign("currency",$mysidia->settings->cost);
 And in template.tpl:
	Code:
	{if $logged_in}
Welcome, <a href="{$home}profile/view/{$username}"><b>{$username}</b></a>! 
<br/>
You have {$cash} <b>{$currency}</b>. 
{else}
Please sign up or log in~! 
{/if}
 And this displays the correct outcome! Yay! 
However, using -
	Code:
	$this->assign("group",$mysidia->user->getusergroup());
 Results in a blank white page. 
 
I'm as of yet unsure how or if the messages work, but I'd like it to just display a number of unread messages a user has, and possibly 0 if there is none? I have no messages, so nothing appears. 

 It looked like it would display more than just a number, but information about the messages. I don't think I need that, but a number next to an envelope icon is floating in my head as a pleasant sight.
Also, thank you very much!